A method for decelerating a motor in a computer numerical controlled machine tool is provided. The method includes calculating a present rate of deceleration DP, for a motor of a motor drive system, based on a present speed SP of the motor, a reference speed SR of the motor, and a reference rate of deceleration DR of the motor. The method also includes decelerating the motor from SP according to DP. The motor drive system comprises a maximum power rating that defines a maximum power, generated by the motor while decelerating, that can be dissipated without overloading the motor drive system. DR is a rate of deceleration such that power, generated by the motor while decelerating from SR according to DR, is equal to the maximum power rating. Power, generated while decelerating the motor from SP according to DP, is equal to or less than the maximum power rating.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for decelerating a motor in a computer numerical controlled (CNC) machine tool, the method comprising: calculating a present rate of deceleration D P , for a motor of a motor drive system in a CNC machine tool, based on a present speed S P of the motor, a reference speed S R of the motor, and a reference rate of deceleration D R of the motor; and decelerating the motor from the present speed S P according to the present rate of deceleration D P , wherein the motor drive system comprises a maximum power rating, the maximum power rating defining a maximum power, generated by the motor while decelerating, that can be dissipated without overloading the motor drive system, wherein the reference rate of deceleration D R is a rate of deceleration such that power, generated by the motor while decelerating from the reference speed S R according to the reference rate of deceleration D R , is equal to the maximum power rating, and wherein power, generated while decelerating the motor from the present speed S P according to the present rate of deceleration D P , is equal to or less than the maximum power rating.
2. The method of claim 1 , wherein the present rate of deceleration D P is given by K 1 ≥ K 2 D R ( S R S P ) 2 . where K 1 and K 2 are calibration constants and D R ( S R S P ) 2 K 1 - K 2 ,
3. The method of claim 2 , wherein K 1 =1 and K 2 =0.
4. The method of claim 1 , wherein if the present speed S P of the motor is greater than the reference speed S R , the present rate of deceleration D P is given by D R ( S R S P ) 2 K 1 - K 2 , where K 1 and K 2 are calibration constants K 1 ≥ K 2 D R ( S R S P ) 2 , and wherein if the present speed S P of the motor is less than or equal to the reference speed S R , the present rate of deceleration D P is equal to the reference rate of deceleration D R .
5. The method of claim 1 , wherein the motor drive system comprises one or more power dissipators, wherein the maximum power rating is an average power rating of the one or more power dissipators, and wherein the method further comprises dissipating, with the one or more power dissipators, power generated while decelerating the motor from the present speed S P according to the present rate of deceleration D P such that the power dissipated is equal to or less than the maximum power rating.
6. The method of claim 5 , wherein the one or more power dissipators comprise at least one of a braking resistor, a transistor, and a capacitor.
7. A computer numerical controlled (CNC) machine tool system comprising: a motor drive system comprising a motor; a controller configured to calculate a present rate of deceleration D P for the motor based on a present speed S P of the motor, a reference speed S R of the motor, and a reference rate of deceleration D R of the motor, the controller further configured to execute an instruction for decelerating the motor from the present speed S P according to the present rate of deceleration D P , wherein the motor drive system comprises a maximum power rating, the maximum power rating defining a maximum power, generated by the motor while decelerating, that can be dissipated without overloading the motor drive system, wherein the reference rate of deceleration D R is a rate of deceleration such that power, generated by the motor while decelerating from the reference speed S R according to the reference rate of deceleration D R , is equal to the maximum power rating, and wherein power, generated while decelerating the motor from the present speed S P according to the present rate of deceleration D P , is equal to or less than the maximum power rating.
8. The system of claim 7 , wherein the motor drive system comprises: a drive unit configured to receive the instruction from the controller and supply power to the motor based on the instruction; and an encoder configured to determine the present speed S P of the motor, the encoder further configured to provide information based on the present speed S P of the motor to the controller, wherein the controller is further configured to receive the information based on the present speed S P .
9. The system of claim 7 , wherein the present rate of deceleration D P is given by D R ( S R S P ) 2 K 1 - K 2 , where K 1 and K 2 are calibration constants and K 1 ≥ K 2 D R ( S R S P ) 2 .
10. The system of claim 9 , wherein K 1 =1 and K 2 =0.
11. The system of claim 7 , wherein if the present speed S P of the motor is greater than the reference speed S R , the present rate of deceleration D P is given by D R ( S R S P ) 2 K 1 - K 2 , where K 1 and K 2 are calibration constants K 1 ≥ K 2 D R ( S R S P ) 2 , and wherein if the present speed S P of the motor is less than or equal to the reference speed S R , the present rate of deceleration D P is equal to the reference rate of deceleration D R .
12. The system of claim 7 , wherein the motor drive system comprises one or more power dissipators, wherein the maximum power rating is an average power rating of the one or more power dissipators, and wherein the controller is further configured to execute an instruction for dissipating, with the one or more power dissipators, power generated while decelerating the motor from the present speed S P according to the present rate of deceleration D P such that the power dissipated is equal to or less than the maximum power rating.
13. The system of claim 12 , wherein the one or more power dissipators comprise at least one of a braking resistor, a transistor, and a capacitor.
14. A controller for a computer numerical controlled (CNC) machine tool system, the controller comprising: a memory module containing executable instructions; and a processor configured to execute the instructions to perform a method for: calculating a present rate of deceleration D P for a motor of a motor drive system in a CNC machine tool based on a present speed S P of the motor, a reference speed S R of the motor, and a reference rate of deceleration D R of the motor; and decelerating the motor from the present speed S P according to the present rate of deceleration D P , wherein the motor drive system comprises a maximum power rating, the maximum power rating defining a maximum power, generated by the motor while decelerating, that can be dissipated without overloading the motor drive system, wherein the reference rate of deceleration D R is a rate of deceleration such that power, generated by the motor while decelerating from the reference speed S R according to the reference rate of deceleration D R , is equal to the maximum power rating, and wherein power, generated while decelerating the motor from the present speed S P according to the present rate of deceleration D P , is equal to or less than the maximum power rating.
15. The controller of claim 14 , wherein the present rate of deceleration D P is given by D R ( S R S P ) 2 K 1 - K 2 , where K 1 and K 2 are calibration constants and K 1 ≥ K 2 D R ( S R S P ) 2 .
16. The controller of claim 15 , wherein K 1 =1 and K 2 =0.
17. The controller of claim 14 , wherein the motor drive system comprises one or more power dissipators, wherein the maximum power rating is an average power rating of the one or more power dissipators, and wherein the method further comprises dissipating, with the one or more power dissipators, power generated while decelerating the motor from the present speed S P according to the present rate of deceleration D P such that the power dissipated is equal to or less than the maximum power rating.
18. A machine-readable medium encoded with executable instructions for decelerating a motor in a computer numerical controlled (CNC) machine tool, the instructions comprising code for: calculating a present rate of deceleration D P , for a motor of a motor drive system in a CNC machine tool, based on a present speed S P of the motor, a reference speed S R of the motor, and a reference rate of deceleration D R of the motor; and decelerating the motor from the present speed S P according to the present rate of deceleration D P , wherein the motor drive system comprises a maximum power rating, the maximum power rating defining a maximum power, generated by the motor while decelerating, that can be dissipated without overloading the motor drive system, wherein the reference rate of deceleration D R is a rate of deceleration such that power, generated by the motor while decelerating from the reference speed S R according to the reference rate of deceleration D R , is equal to the maximum power rating, and wherein power, generated while decelerating the motor from the present speed S P according to the present rate of deceleration D P , is equal to or less than the maximum power rating.
19. The machine-readable medium of claim 18 , wherein the present rate of deceleration D P is given by D R ( S R S P ) 2 K 1 - K 2 , where K 1 and K 2 are calibration constants and K 1 ≥ K 2 D R ( S R S P ) 2 .
20. The machine-readable medium of claim 19 , wherein K 1 =1 and K 2 =0.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
March 30, 2010
October 30, 2012
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